While the debate as to whether or not MDMA is toxic in its own accord rages on, it is well known that the repetitive insufflation (snorting) of any substance is not very good for your mucous membranes. Excessive use can induce bleeding, damage the cartilage and lining of the nostrils, burn the throat, and cause other nasal and sinus trauma.

Infrequent use should not be a problem, however one must realize that insufflation causes most substances to come on stronger, faster, and with a shorter duration, as well as requiring less substance. If one is already intoxicated or misjudges a dose, the chance of an overdose is slightly greater due a steeper dose-response curve.

There are also potential toxicity issues associated with the use of stimulants and specifically the MDMA family. Some of the animal toxicity models are based on peak blood levels, which indicates that neuronal damage might be more likely if one has a higher peak plasma concentration. Snorting MDMA causes the blood levels to spike higher (per milligram of material) than oral dosing. However, other animal toxicity models are based on total exposure ("area under the curve") and not as much on peaks. It could be that insufflating moderate doses of MDMA a few times could actually be less likely to induce the type of serotonergic neurotoxicity demonstrated in very high dose animal experiments.

All risks increase with dose and frequency. No matter what, snorting MDMA is worse if it means you wind up doing more than you planned, make worse decisions, or do it too frequently.